Here's why live oaks and crape myrtles are dying in Redlands

Quite a bit has been written in the last few weeks about the state of trees in Redlands. I wish to add one more voice to the fray. Live oaks (Quercus agrifolia), which make up the bulk of the oaks in question, can live up to 300 years in their native environment. This is due to the extreme conditions that they face, such as drought, soil deprivation and heat. These conditions create a very slow metabolic rate in the trees, with the resulting narrow growth rings, hard wood and gnarled look that we recognize as oaks.

Now, transplant these oaks into an urban environment, feed and water them a lot, and we have very happy young trees that grow faster and weaker, have a much higher metabolic rate and burn themselves out in about 50 or 75 years. By making them happy, we have shortened their life span by three-fourths. It is only at the end of this life span that most of the problems seem to pop up.

One exception is oak root fungus, which seems to rear its ugly head in south Redlands from time to time. Oak root fungus, more properly called armillaria root fungus, is also called honey fungus, mushroom root rot and shoestring fungus. Armillaria mellea is a common soil-borne fungus found in temperate regions throughout the world. More than 50 distinct varieties of the fungus attack the roots of hardwoods, conifers and herbaceous shrubs.

The fungus begins rotting the roots when plants are under stress. The rotting roots deny infected trees water and nutrients. The fungus works its way up the tree, eventually encircling the trunk. Armillaria mellea develops most rapidly under warm, moist conditions. It can survive indefinitely on diseased or dead roots. Leaves of trees and plants infected by Armillaria fungi usually turn yellow; they are smaller and there are fewer of them. Some plants deteriorate slowly over years; others wilt quickly and die abruptly. Trees often suffer infection for years before the fungus is diagnosed.

As the trees die or reach a critical stage, we need to now remove them, allow the underlying soil to air out (this precludes the use of a stump grinder -- the stumps will have to be removed) and replant with a more resistant tree. I nominate the holly oak (Quercus ilex), which is a much more resistant and tolerant species, and looks and grows very much like the live oak. In short, it works and plays well with others.

The other tree problem Redlands has is one of neglect and perhaps laziness. Surely, a lack of information plays a large part in the problem.

Crape myrtles, the symbol of Redlands' streets for many years, are being slowly but surely liquidated. Their beautiful blonde bark is also very soft, and lawn mowers and weed whips are chopping through it. This exposes the cambium or living layer of the tree to dehydration and sun, which kills the tree.

Take a look around Redlands. Look first at the spectacular foliage and incredible flowers of crape myrtles that are not in lawns. Then look at many of them in parkways and lawns -- half-dead, stalky and few flowers, if any. Take a look at the base of the trunks. Scars, cuts and chewed-up bark are proof that the trees have been banged up by lawn mowers and weed whips.

Plastic trunk wraps are not the solution to this problem. Self-propelled mowers hit hard enough to bruise the tree even through the wrap. Gas-powered weed whips are strong enough to lift the wrap if they are presented at the right angle. The only solution is abstinence. Clean an area around the tree and trim the lawn in this area only with hand tools. Sound too hard? You are hopefully sparing a tree. It's worth it.

Yes, it's too late for many of the crape myrtles. They are dying, and as such will be removed. I only hope that they will be replaced, and the next generation will be better taken care of.

From the earth we are born, to the earth we return, and in between we garden.